Severe Idle problem...

[92Fwd4Me]

Hey guys...this may have been posted. I looked an nothing really seems to fit my problem.

Little history.

I have never passed a state emissions test. Ever. So as preparation I replaced the 02 sensor (its a 92 Tsi FWD). Then I laid in some Royal Purple, and changed the thermostat (last time I drove it before putting up for the winter....I went 10 miles in the snow and it never came off cold). Thermostat was dookied up bad. Was good call on that. With the new oil it holds MUCH better oil pressure at idle. Used to hover right about the absolute zero mark....now it holds strong at the middle tic.

BUT.....(always a but with a DSM )


The idle is very very hard. It bounces consistently between 1200 and 1500 rpm. Nothing I do to idle set screw changes anything. Throttle response is fast....and the power feels better then it ever has....but when you let off the throttle parked it spools down slowwwww and then goes back into its bounce. It had done this before a couple times.....but a restart always fixed my problem (leads me to think a sensor of some kind). I also have to shamefully admit the gas that has been sittin in it for months now while I drove my legal car was ..... 89 octane and like I said its been sittin in the tank for awhile....stagnant. Yes....first plan of attack is finish off remaining gas in the tank and loading up 92 octane with some gas additive to boot. It had a REAL bad knock when I started it....that went away as I ran it. The idle was at first well over 2000, but again that also came down to the 1200-1500 bounce.

Things I am thinking:

Plugs
EGR valve
Air Filter (although should be new)

Any ideas or troubleshooting I can do....I will openly listen to as law. Thanks again.


P.S. Also had to change the battery....it was dead. And no CEL is on...never does.

 

[ddavisaf]

Change the ISC.
It's located on the back bottom of the throttle body.

If you're changing the plugs, make sure you put in NGK BPR6ES' and gap them to .028".

 

[92Fwd4Me]

This is sad. I work on jet engines for a living to boot.



What is ISC?

And got ya on the spark plugs


From my reading....the EGR does not really effect idle that I can see does it??

 

[larsenracing]

The isc it Idle Speed Controller. this controles air flow which is extra air that is bypassed by the throttle body and basically keeps the R's up when turning on the AC or headlights and so on also when starting cold that is what keeps the R's above 1000 till it worms up. but I'm sure it does more i just don't know what else it all does I'm sure there is a forum on it or someone else knows a little more about it. Hope this helps ya a little.

 

[92Fwd4Me]

Whoot. $349.00 from Satan...


Idle problem solved.


Too bad I didnt get the thermostat seated well and it leaked all over. Ahh well. New gasket....no biggy. I did have to adjust the BISS to get it back down to abouit 700rpm at idle with normal temps. It was at about 1200rpm. I did adjust this before....so its actually a counter adjustment


Thanks for the help.


P.S Just to clarify.....I didnt just change it, I took it out....shot pins 1-2 (dead), 3-4(open) and 5-6 (open) so it was surely shot to hell. I checked the new one at the desk at Satan....and the guy looked at me like I was a freak. Had to make sure

 

[BaddAssGst]

Damn, should've found someone who had one cheaper then that. No reason to pay 350 bucks for one. I guess it's all said and done now though. Congrats on a fine idling DSM. There aren't to many of us around.

 

[92awddsm]

Next time around(and there will be a next time) go to the local scrapyard and get one of the black top isc's from a hyundai. Thats what I did and it has lasted a lot longer that the stock mitsu pieces I have purchased.

Also, go ahead and replace the cat converter before you try to smog it again.